the outset no they're testing to see if the acoustics are as good as they had hoped obviously they need an audience in its place they use specially made lengths of fabric a full concert hall sounds very different than an empty one. firing the gun allows them to measure reverberation. but why don't they just use an instrument. there are several ways of measuring reverberations what's important is to make a noise that can be easily reproduced the exact sound made by a musical instrument can't always be reproduced to report the sound a gunshot makes can be consequence and it covers the full range of frequencies and has sufficient energy especially in the lower frequencies so the volume and so on pattern of a fired hand gun is always the same. at strategic spots in the concert hall the acoustic technicians measure how long it takes for the sound of the gunshot to die